在阴离子表面活性剂存在下以2-(5'-氯-2'-吡啶偶氮)-5-二甲氨基苯胺分光光度测定银

本文提出了一个简便、灵敏而有选择性的测定银的分光光度法.方法基于银(I)在阴离子表面活性剂十二烷基硫酸钠存在下与2-(5'-氯-2'-吡啶偶氮)-5-二甲氨基苯胺(简称5-Cl-PADMA,1)的颜色反应.银络合物的吸收峰位于500nm,在530nm以显色剂参比摩尔吸光系数6.7×10~4.在pH6～10.5之间吸光值恒定.银浓度在0～1.2ppm时服从Beer定律.用等摩尔连续变化法和摩尔比例法测得络合物中Ag(I)与5-Cl-PADMA的比例为1∶2.在掩蔽剂柠檬酸盐和Ca-CyDTA存在下,该反应对银的测定是选择性的.方法已用于铀和铝试样中银的测定.     

In-situ growth of Ca/P salt on Ti surface induced by femtosecond lasers in hydroxyapatite suspension

Pure Ti plate surfaces are micro-ablated by femtosecond lasers in the ambience of hydroxyapatite suspension. It is found that three-stage hierarchical surface structures are produced with various laser energies. When the laser energy is 150 μJ, a lava-like structure with a distribution of nanoholes is dispersed evenly on the laser ablated surface. While in the case of 300 μJ, the grooves-and-islands micro-patterns covered with nanoparticles are generated on the surface. Remarkably, Ca/P based substances are revealed to firmly deposit on the micro-structured surfaces. More phosphate growth is seen for the higher laser energy. Discussions suggest that the additional elements deposition could be attributed to the chemical reaction of plasma related ions in the suspension and their subsequent crystallisation on the fresh surfaces of Ti plate due to the femtosecond laser ablation.     

微量希土的螯合滴定

直接或间接螯合滴定常量希土元素已有评述^[1].但有关微量希土元素的螯合滴定之报导不多,Flaschka^[2]曾借铬黑T等作指示剂于直接或间接滴定少量轻希土元素和钇.程广禄^[3]曾报告借PAN作指示剂,以铜返滴定微量希土元素.Лауэр等^[4]曾借纸层析法分离后,继以偶氮胂作指示剂,用氯化镧溶液返滴定以测定个别希土元素.